A Beginner's Guide to Getting Started with Deno

If you're a developer looking to explore modern JavaScript and TypeScript runtime environments, you've likely heard of Deno. Created by Ryan Dahl, the original creator of Node.js, Deno is a secure, modern runtime for JavaScript and TypeScript that addresses many of the shortcomings of its predecessor. Whether you're a seasoned developer or just starting out, this guide will walk you through the basics of getting started with Deno.

In this beginner-friendly guide, we’ll cover:

• What Deno is and why it’s gaining popularity
• Key features that set Deno apart from Node.js
• How to install Deno on your system
• Running your first Deno script
• Exploring Deno’s built-in tools and features

Let’s dive in!

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What is Deno?

Deno is a runtime environment for JavaScript and TypeScript, designed to be secure, simple, and developer-friendly. Unlike Node.js, which relies on external package managers like npm, Deno has a built-in module system and comes with first-class support for TypeScript out of the box.

Why Choose Deno?

Deno was created to address some of the pain points developers face with Node.js, such as:

• Security: Deno runs scripts in a sandboxed environment, requiring explicit permissions for file system access, network requests, and more.
• TypeScript Support: Deno natively supports TypeScript without the need for additional configuration or tools.
• No node_modules: Deno uses ES Modules and fetches dependencies directly from URLs, eliminating the need for a node_modules folder.
• Built-in Utilities: Deno comes with a suite of built-in tools, such as a linter, formatter, and test runner.

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Installing Deno

Installing Deno is quick and straightforward. It’s available for all major operating systems, including Windows, macOS, and Linux.

Step 1: Install Deno

To install Deno, open your terminal and run the following command:

• Using Shell (macOS/Linux):

  curl -fsSL https://deno.land/install.sh | sh
  

• Using PowerShell (Windows):

  iwr https://deno.land/install.ps1 -useb | iex
  

Alternatively, you can use a package manager like Homebrew (macOS) or Chocolatey (Windows):

• Homebrew (macOS):

  brew install deno
  

• Chocolatey (Windows):

  choco install deno
  

Step 2: Verify Installation

Once installed, verify that Deno is working by running:

deno --version

You should see the installed version of Deno, along with its V8 JavaScript engine and TypeScript compiler versions.

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Running Your First Deno Script

Now that Deno is installed, let’s run a simple script to see it in action.

Step 1: Create a Script

Create a new file called hello.ts and add the following code:

console.log("Hello, Deno!");

Step 2: Run the Script

Run the script using the deno run command:

deno run hello.ts

You should see the output:

Hello, Deno!

Congratulations! You’ve just run your first Deno script.

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Exploring Deno’s Built-in Features

One of the standout features of Deno is its suite of built-in tools. Let’s take a closer look at some of them.

1. Deno’s Permission System

Deno enforces strict security by default. For example, if your script tries to access the file system or make a network request, you’ll need to explicitly grant permissions.

Example: File System Access

Create a script called read_file.ts:

const data = await Deno.readTextFile("example.txt");
console.log(data);

Run the script with the necessary permission:

deno run --allow-read read_file.ts

Without the --allow-read flag, Deno will throw a permission error.

2. Built-in Formatter and Linter

Deno includes a built-in formatter and linter to help you write clean, consistent code.

• Format Code:

  deno fmt
  

• Lint Code:

  deno lint
  

3. Testing with Deno

Deno has a built-in test runner, making it easy to write and run tests without additional libraries.

Example: Writing a Test

Create a file called example_test.ts:

import { assertEquals } from "https://deno.land/[email protected]/testing/asserts.ts";

Deno.test("simple test", () => {
  const result = 1 + 1;
  assertEquals(result, 2);
});

Run the test using:

deno test

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Where to Go From Here?

Now that you’ve taken your first steps with Deno, here are some resources to help you dive deeper:

• Official Documentation: https://deno.land/manual
• Deno Standard Library: https://deno.land/std
• Third-Party Modules: https://deno.land/x

Deno is a powerful and modern runtime that’s worth exploring, especially if you’re looking for a fresh approach to building secure and efficient applications. With its built-in tools, TypeScript support, and focus on simplicity, Deno is quickly becoming a favorite among developers.

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Are you ready to start building with Deno? Let us know in the comments what you’re excited to create!